This invention relates in general to electrical connectors and in particular to fluid-proof electrical connectors suitable for mating or unmating underwater.
U.S. Pat. No. 3,277,424 is illustrative of a vented pin-and-socket connector system of a type widely used to provide underwater-mateable connections. The major drawback to this system is that the mating forces are very high and the production quality control is very difficult to achieve. Both of these problems relate directly to the design of the electrical contact area. The split-ring contact system was incorporated into the original design to allow the contact to be wiped off by the leading insulation surface. Unfortunately this type of contact must have very tight fit in order to provide the needed high local pressure after mating to ensure electrical contact and low resistance. This produces high insertion force. The fact that the insulating surfaces and the contact surface are all of the same diameter compounds this problem because there is literally an interference fit throughout the entire length of the mating travel. The contact area is further complicated by the fact that molding rubber around this shape in a production scenario always leaves rubber flashing extruded through the contact. This flashing is very difficult to remove from within the small cavity in which the contact is located and in operation the flashing will often stretch across the contact, providing reduced or broken contact quality and even higher mating forces. The fact that the contact is a split-ring also makes the connector pressure sensitive. Even though the contact pin itself is pressure balanced through the vent, the bulk modulus of the solid metal male pin is sufficiently higher than the split female ring that pressure is free to compress the socket diameter and make it nearly impossible for a diver to mate the connectors at the extended operating depths of todays diving scenarios. A connector mated at the surface and then submerged is vulnerable to the same effects and can become nearly impossible to unmate. The rubber-to-rubber seals tend to compress together and have much lower coeffients of friction, so the insulating seals themselves are not the problem. Present designs with the split-ring also frequently cause damage to the leading edge of the male pin insulation so that it rapidly wears out and no longer provides a proper wiping function.